| A geode is a beautiful mineral
formation that usually consists of an exterior shell of
chalcedony
(very
fine-grained quartz), with other
minerals and / or crystals lining the interior.
The name "geode" is derived from
the Greek word "geo" that refers to the shape of the earth,
since most geodes are spherical.
A geode can form in any cavity within rock.
Typically,
bubbles of gas form in cooling
ash beds.
When such a gas bubble gets “frozen” in a particular location
when the silica-rich ash/dust hardens the process of geode-formation
begins. The partial or complete filling of
the
bubble
with the minerals that may lead to the crystaline structures that make
geodes so attractive may occur
soon afterwards - or millions of years
later - and can include a wide range of different minerals.
Geodes can be beautiful to look at and are available for sale from many
crysyal and other shops. Click here to view pretty
little geodes for sale online (Prices from £4.50).
What can be even more fun is to find ones own geodes. It
can be difficult to tell if a rock is a geode or not without
craking
it open to view the inside - which is why so many people find this an
interesting and exciting hobby.
Geodes are sometimes known as "thunder
eggs". |
